Facts from FishBase, SRAC and EFish.

There are at least 17 different species of gambusia native to the US and at least 3 more non-native ones here. Two of the non-native species are the most common and one covers the south 3/4ths of east coast area and another the Miss. drainage.

The ones I checked average 50 offspring per hatch/birth , once a month , April to Sept. That is 250-300 offspring a year. Most have a fast population doubling time 15 mths but one of the more common species has a medium population (1.4 - 4.4 yr)doubling time. There are several species which are native to small specific areas of Texas which has more different species than any other state or area. Avg. length 3-6 cm ,age 2 yrs. Food -zooplank- cladocerans , polychaetes/worms/larva , insects , bony fish (cannibal),other terrest.invertebrates. Climate - subtropical; 12 – 29°C.

Fatheads. Fast population doubling time of 15 mths. Spawns April - Aug. and average fecundity 6,803-10,164 . Age 2 yrs , length 10 cm. Food - plank.- copepods, benth. crust.- ostracods ,insects ,benthic- algae/weeds , bryozoan statoblasts, other. Climate- temperate; 0 – 33°C. Females spawn at frequent intervals, up to several times a week. A fractional spawner.

Here is a link. to some pics

http://www.fishbase.org/ComNames/ComName...5gambusia%25%27